Cheshire Collimator: Comprehensive Guide to Models and Usage [2026]

A Cheshire collimator is an eyepiece tool that is used for collimating a telescope, which means aligning its optical elements to achieve the best possible image quality. 

The Cheshire collimator is particularly useful for collimating the secondary mirror in a reflecting telescope, which can be difficult to align without a specialized tool. It can also be used to align the primary mirror or lens elements in refracting telescopes.

Small faint circles in the telescope image can be caused by misaligned mirrors, which can be easily corrected using a Cheshire Collimator during setup.

Cheshire collimators come in various designs and sizes, but the basic principles of operation are the same. They are widely used by amateur astronomers for collimating their telescopes, as they are relatively inexpensive and easy to use.

Different models of the Cheshire collimator are available in the market, each with unique features and benefits. 

In this article, we will provide an overview of the different models of the Cheshire collimator to help you make an informed decision on which one to use for your telescope.

Best Cheshire Collimators

Some Cheshire collimators stand out from the rest due to their exceptional quality and user-friendly design. 

Let’s discuss some of the best Cheshire collimators currently available.

Farpoint reflective Cheshire collimator, 1.25″

is an excellent choice for those looking for a high-quality collimator. It is designed to work with 1.25″ focusers and has a reflective peephole that provides a clear and bright view of the illuminated wire. 

The collimator is made of high-quality materials and has a sturdy construction that ensures long-lasting performance. 

Orion Cheshire collimator

is a type of Cheshire collimator designed specifically for aligning mirrors in reflecting telescopes. It is made by Orion Telescopes & Binoculars, a popular brand in the astronomy community.

The Orion collimating eyepiece is a simple and effective tool that can help you achieve precise alignment of your telescope’s mirrors for optimal viewing performance. 

It consists of a black anodized aluminum tube with a peephole at one end and a reflective surface at the other end.

Celestron Cheshire collimator

is a specialized tool designed for the precise collimation of Newtonian telescopes. It is a 1-1/4” eyepiece that can be fitted into any 1¼” focuser or diagonal. 

The eyepiece is an essential tool for ensuring the mirrors in the telescope are properly aligned for optimal viewing.

The Celestron Collimation Eyepiece is very easy to use and provides a much more accurate alignment than a simple collimation tool. 

With the help of the Celestron Collimation Eyepiece, users can achieve proper alignment of the telescope’s mirrors in no time. It is an indispensable tool for any serious astronomer who wants to get the most out of their telescope.

COLPARY 1.25Inch Metal Collimating Cheshire Eyepiece 

The is a high-quality tool ideal for precise Newtonian collimation. Made from durable, anti-rust, and wear-resistant materials, this collimator ensures you can use it for a long time. 

With its more accurate collimation than the normal collimation tool, this eyepiece can help you better enjoy the stars.

Astromania 1.25″ Cheshire Collimating Eyepiece

The is a handy tool for aligning the optics of Newtonian reflectors, Dobsonian reflectors, and Schmidt-Cassegrain Telescopes (SCTs). 

It fits in 1.25″ focusers and is easy to use; simply cap the telescope, remove the diagonal, and place the eyepiece directly in the focuser.

This short collimator for mirror (reflector) telescopes has a 45-degree plate for easier visual accuracy, and its aluminum construction makes it lightweight and durable. 

A . This collimation eyepiece can precisely collimate the Newtonian and Schmidt-Cassegrain reflector telescopes, ensuring better image quality. 

Svbony 1.25″ Cheshire Collimator

The is an essential tool for collimating your Newtonian and SCT reflector telescopes. It can also be used for accurately aligning refractor optics. 

The SV197 eyepiece features a peephole at the top, allowing you to see the calibration result directly.

Precision machined from high-quality aluminum, this collimating eyepiece is durable and built to last. It features fine cross hairs and a clear, bright mirror with a sighting hole for easy alignment. 

Alstar 1.25Inch Metal Collimating Cheshire Eyepiece

The is a valuable tool for aligning the optics of Newtonian reflectors, Dobsonian reflectors, and Schmidt-Cassegrain Telescopes (SCTs). 

Its design fits perfectly in 1.25″ focusers and is easy to use. Simply cap the telescope, remove the diagonal, and place the eyepiece directly in the focuser.

This long-version collimation eyepiece is made of high-quality aluminum, making it durable and resistant to wear and tear. The crosshair at the bottom allows for quick and precise centering of the optics. 

DIY Cheshire Collimator

A DIY Cheshire Collimator can be made using basic tools and materials. To make a DIY Cheshire Collimator, you will need a tube (such as a piece of PVC pipe or an old eyepiece barrel), a drill, a file, a wire or crosshairs, and a peephole (which can be made by drilling a small hole in the tube and filing it to shape).

It involves creating a peephole at the end of a tube and inserting a wire or crosshairs that can be viewed through the peephole. 

The wire or crosshairs should be positioned at the center of the tube, and the peephole should be located at the end of the tube opposite the wire. Once assembled, the collimator can be used to align your telescope’s optics.

A homemade Cheshire Collimator can be an inexpensive option for amateur astronomers who want to save money or enjoy building their own equipment.

How to use a Cheshire Collimator

Using a Cheshire collimator is a straightforward process that involves inserting the collimator into the telescope’s focuser and aligning the optics by adjusting the secondary and primary mirrors. 

To use a Cheshire collimator, follow these steps:

• Insert the Cheshire collimator into the focuser and secure it in place.
• Look through the peephole and adjust the primary mirror so that it is centered in the view.
• Adjust the secondary mirror so that its reflection appears in the peephole and is centered in the view.
• Adjust the secondary mirror’s tilt and rotation until the reflection appears as a round circle or a centered crosshair.
• Repeat the process until the reflection appears perfectly aligned in the peephole.

Using a Cheshire Collimator when the Secondary mirror is Offset

When using a Cheshire collimator with a telescope that has an offset secondary mirror, the process is slightly different. In this case, do the following: 

• Insert the Cheshire collimator into the focuser of the telescope.
• Adjust the secondary mirror until its reflection appears in the peephole of the Cheshire collimator.
• Adjust the tilt and rotation of the secondary mirror until its reflection appears as a centered circle or crosshair in the peephole.
• Adjust the primary mirror so that its reflection appears in the peephole and is centered in the view.
• Check the tilt and rotation of the secondary mirror again to ensure correct alignment.
• Make adjustments if necessary until the reflection appears perfectly aligned in the peephole.

Using a Cheshire Collimator when the primary mirror is off-center

• To check whether the primary mirror is off-center, place the Cheshire collimator in the focuser, and look through the eyepiece. 
• If the reflection of the collimator is not centered in the secondary mirror, the primary mirror is likely off-center.
• You need to make small adjustments to the three mirror clips or screws holding the mirror in place to adjust the primary mirror. 
• Use the Cheshire collimator to align the primary mirror by ensuring that the collimator’s reflection is centered in the secondary mirror.

Tips for accurate alignment with a Cheshire Collimator

Here are some tips for achieving accurate alignment with a Cheshire collimator:

Clean your optics

Before using the Cheshire collimator, ensure your telescope optics are clean and free of dust or debris. This will help you get a more accurate alignment.

Adjust the secondary mirror

If you have a reflector telescope, adjust the secondary mirror to be centered on the focuser. This will make the collimation process easier.

Use a dark room or cover your primary mirror

When using a Cheshire collimator, it’s best to work in a dark room or cover the primary mirror to reduce external light interference. This will make it easier to see the collimation marks on the Cheshire.

Align the collimation marks

The goal of collimation is to align the collimation marks on the Cheshire collimator with the reflection of your telescope’s primary mirror. Take your time and make small adjustments until the marks are aligned.

Repeat the process

After making adjustments, double-check your alignment with the Cheshire collimator. Repeat the process until the collimation marks are perfectly aligned.

Takeaway: Cheshire Collimator eyepiece is a must-have tool for precision alignment

The Cheshire collimator is a simple but effective tool for aligning a telescope’s optics. Various Cheshire collimator models are available on the market, each with its own features and specifications. 

Observing under ambient light can make aligning the mirrors in a telescope more challenging, but a Cheshire Collimator makes the process easier and more precise.

With the right Cheshire collimator and a bit of practice, you can achieve optimal alignment of your telescope’s optics and enhance your stargazing experience.